| MSN Building Services Ltd | Construction | 2021 |
| Mthl Fleet Services Truck & Trailer Engineering Limited | Wholesale & retail | 1999 |
| Mthl Fleet Services Truck & Trailer Parts Limited | Wholesale & retail | 1999 |
| Mulberry Court (Surbiton) Management Limited | Households | 2002 |
| Mulgrave Heating Limited | Construction | 2003 |
| Mulgrave Road Limited Partnership | | 1988 |
| Multi-Dimension Re:Align Limited | Professional & scientific | 2005 |
| Multiple Focus Ltd | Information & communication | 1997 |
| Munch @ Coughlans Limited | Professional & scientific | 1962 |
| Murphy & Associates Ltd | Professional & scientific | 2021 |
| Murray Holdings Limited | Financial services | 2003 |
| Music Illuminated | Education | 1998 |
| MUSIC4MEDIA Limited | Information & communication | 2004 |
| Mutute Ltd | Education | 2011 |
| MVE Consulting Ltd | Real estate | 2019 |
| MVP Optics Limited | Health & social care | 2016 |
| Mycoplasma Experience Limited | Professional & scientific | 1988 |
| Mycrown Restaurant Limited | Hospitality | 1999 |
| MZ Stores Limited | Wholesale & retail | 2011 |
| N. Morrison & Sons Limited | Construction | 2006 |
| N. Shipley & Co. Limited | Transport & logistics | 1987 |
| N.H.G. Timber Limited | Wholesale & retail | 1981 |
| N1 Tyres Sutton Ltd | Wholesale & retail | 2023 |
| Nader Construction Ltd. | Construction | 2003 |
| Naik Holdings Ltd | Information & communication | 2021 |
| NAJ Ltd | Wholesale & retail | 2005 |
| NAK Construction Limited | Construction | 2005 |
| NAM Software Services Ltd | Information & communication | 2006 |
| Namcrest Limited | | 1976 |
| Namyo Technologies Ltd | Information & communication | 2014 |
| Nancare Supported Living Limited | Public administration | 2023 |
| Nannywage Limited | Professional & scientific | 2002 |
| Nanosys Limited | Information & communication | 1994 |
| NAQ Holding Ltd | Financial services | 2024 |
| NAQ Property Management Ltd | Financial services | 2024 |
| Nathan Installations Limited | Professional & scientific | 1989 |
| National Upskill Limited | Administrative & support | 2003 |
| Natural Rhythm Limited | Arts & recreation | 2004 |
| Naturaloverz Ltd | Manufacturing | 2019 |
| Nauticall Limited | Information & communication | 2000 |
| Nauvoo PAK. Ventures Limited | Professional & scientific | 1998 |
| Naveta Constructions Limited | | 1973 |
| Nawal Traders Ltd | Wholesale & retail | 2024 |
| NCI Europe Limited | Information & communication | 1998 |
| NCI Systems Limited | Information & communication | 2000 |
| NDP Solutions Limited | Information & communication | 2001 |
| Needthis Limited | Professional & scientific | 2005 |
| Negrov Ltd | Transport & logistics | 2015 |
| Neil Phillips Design Limited | Other services | 2005 |
| Nelima's Kitchen Ltd | Hospitality | 2020 |
| Nelson Properties Holding Limited | Real estate | 2023 |
| Nelsons' (Horsham) Limited | | 1969 |
| Nepal Leprosy Trust | Health & social care | 2000 |
| Nepal Leprosy Trust Services Ltd | Wholesale & retail | 1996 |
| Nestia Creative Ltd | Wholesale & retail | 2016 |
| Nestwell Marketing Ltd | Professional & scientific | 2000 |
| NET Holdings Group Limited | Information & communication | 2021 |
| Netherby Park Limited | Households | 1985 |
| Netley Property Limited | Real estate | 1985 |
| Netrise Limited | Information & communication | 1999 |
| Netsmart Enterprises Limited | Information & communication | 2003 |
| Netspan Consultants Limited | Information & communication | 2000 |
| Network Electrical Services Limited | Administrative & support | 2005 |
| Network Media Communications Limited | Manufacturing | 1996 |
| Network Software Systems Limited | Information & communication | 1998 |
| Network XP Consultancy Limited | Wholesale & retail | 2002 |
| Networks Inc Limited | Professional & scientific | 1995 |
| Neuhart Property Limited | Professional & scientific | 1966 |
| Neutron Properties Ltd | Hospitality | 2022 |
| Nevrun Limited | Information & communication | 1988 |
| New Ashgate Gallery Trust Limited(The) | Arts & recreation | 1977 |
| New Hope Medical Consultancy Ltd | Health & social care | 2019 |
| New Level Interiors Ltd | Construction | 2007 |
| New Lick Limited | Professional & scientific | 1999 |
| New Malden Tennis Squash and Badminton Club Limited | Arts & recreation | 1980 |
| New Orange Tree Theatre Trust | Arts & recreation | 1987 |
| New Zealand Avenue Properties 13/19 Ltd | Households | 1999 |
| New Zealand Golf Club,Limited | Arts & recreation | 1908 |
| Newer Worlds Ltd | Professional & scientific | 2006 |
| Newholme Court Residents Company Limited | Real estate | 1998 |
| Newlands Lodge Management Co Limited | Households | 1994 |
| News Presenters Limited | Administrative & support | 2005 |
| Newstop 2000 Limited | Hospitality | 1982 |
| Newstore Investments Limited | Real estate | 1999 |
| Newtech Marketing Limited | Financial services | 1983 |
| Nexco UK Limited | Professional & scientific | 2005 |
| Next Step Homes Limited | Construction | 2016 |
| Next Step Pathways Group CIC | Administrative & support | 2026 |
| Niall Clutton Photography Limited | Professional & scientific | 2005 |
| Nicha Group Ltd | Wholesale & retail | 2021 |
| Niche by Suzanne Neville Limited | Wholesale & retail | 2006 |
| Nicholas Lawson Limited | Professional & scientific | 1964 |
| Nick Powers Ltd | Information & communication | 2003 |
| Nick's Garden Services Limited | Administrative & support | 2002 |
| Nicoms Limited | Professional & scientific | 1989 |
| Nightingale Residents' Management Limited | Construction | 1992 |
| Nightingales Guildford Limited | Real estate | 1996 |
| Nihad Properties Ltd | Real estate | 1995 |
| Nihil Solutions Ltd | Information & communication | 2016 |
| Nikem Medicare Limited | Health & social care | 2013 |